JP7545889B2 - Polyhydric hydroxy resin, epoxy resin, epoxy resin composition, and cured product thereof - Google Patents

Description

The present invention relates to polyhydric hydroxyl resins, epoxy resins, epoxy resin compositions, and epoxy resin cured products thereof, and more specifically to epoxy resin compositions useful as insulating materials for electrical and electronic components such as semiconductor encapsulation, laminates, and heat dissipation substrates.

Epoxy resins have been used industrially for a wide range of applications, but the performance requirements have become increasingly sophisticated in recent years. For example, a representative field of resin compositions based on epoxy resins is semiconductor encapsulation materials. With the increase in the integration density of semiconductor elements, package sizes are becoming larger and thinner, and the mounting method is also moving toward surface mounting, so the development of materials with excellent solder heat resistance is desired. Therefore, as encapsulation materials, in addition to low moisture absorption, there is a strong demand for improved adhesion and adhesion at the interface of different materials such as lead frames and chips. Similarly, in circuit board materials, in addition to low moisture absorption, high heat resistance, and high adhesion from the perspective of improving solder heat resistance, there is a demand for materials with excellent low dielectric properties from the perspective of reducing dielectric loss. In addition, reliability is important for applications such as in-vehicle devices, and there is a demand for a reduction in the amount of extracted chlorine ions in the cured product. For this reason, there has been a demand for a reduction in the chlorine content of the resin itself.

In light of the above background, various epoxy resins and epoxy resin curing agents have been studied. Naphthalene-based resins are known as an example of an epoxy resin curing agent, and Patent Document 1 shows the application of naphthol aralkyl resins to semiconductor encapsulation materials, and describes their excellent flame retardancy, low moisture absorption, low thermal expansion, and other properties. Patent Document 2 also proposes a curing agent having a biphenyl structure, and describes its effectiveness in improving flame retardancy. However, both naphthol aralkyl resins and biphenyl aralkyl resins have the disadvantage of poor curing properties, high softening points and melt viscosities, and insufficient fluidity during molding.

Furthermore, well-known bisphenol-type epoxy resins are widely used because they are liquid at room temperature, have excellent workability, and are easily mixed with curing agents, additives, etc., but have problems with heat resistance and moisture resistance. Also, o-cresol novolac-type epoxy resins are known as resins with improved heat resistance, but are insufficient in terms of flame retardancy. Patent Document 3 proposes an aralkyl resin using a xylylene-skeleton condensing agent that has excellent heat resistance, moisture resistance, and workability, but makes no mention of chlorine-based impurities.

JP 2005-344081 A Japanese Patent Application Publication No. 11-140166 Japanese Patent Application Publication No. 8-333428

The object of the present invention is to provide an epoxy resin composition that is capable of good melt-kneading at 100°C or less, has excellent solvent solubility, and gives a cured product that is also excellent in thermal decomposition stability, low dielectric properties, and reliability, and is useful for sealing electric and electronic components, as a circuit board material, and to provide a cured product of the composition. Another object is to provide an epoxy resin used in the epoxy resin composition, and a polyhydric hydroxyl resin suitable as an intermediate for the epoxy resin.

The inventors conducted extensive research and discovered that polyhydric hydroxyl resins and epoxy resins having specific structures are expected to solve the above problems, and that the cured products thereof exhibit excellent thermal decomposition stability, low dielectric properties, and reliability.

（ここで、ｎは０～２０の数を示し、Ｇはグリシジル基を示し、Ｒ^１、Ｒ^２は独立して水素原子または炭素数１～１０の一価の炭化水素基を示す。） That is, the present invention relates to an epoxy resin represented by the following general formula (1), characterized in that the epoxy equivalent is in the range of 250 to 500 g/eq.

(wherein n is a number from 0 to 20, G is a glycidyl group, and R ¹ and R ² are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms.)

（ここで、ｎは０～２０の数を示し、Ｒ^１、Ｒ^２は独立して水素原子または炭素数１～１０の一価の炭化水素基を示す。） The polyhydric hydroxy resin is represented by the following general formula (2), and is characterized in that the OH equivalent is in the range of 200 to 450 g/eq.

(wherein n is a number from 0 to 20, and R ¹ and R ² each independently represent a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms.)

The present invention further relates to an epoxy resin composition comprising an epoxy resin and a curing agent, the epoxy resin composition being characterized in that it contains the above-described epoxy resin as an essential component as part or all of the epoxy resin, and to an epoxy resin cured product characterized in that it is obtained by curing the epoxy resin cured product.

The present invention also provides a resin composition that contains the polyhydroxy resin described above as an essential component, and a cured resin product that is obtained by curing the composition.

The epoxy resin of the present invention has good melt-kneadability, excellent solvent solubility, and a particularly low chlorine content in the resin itself, making it suitable for use in epoxy resin compositions and their cured products used in applications such as lamination, molding, casting, and adhesion. Furthermore, this cured product also has excellent thermal decomposition stability, low dielectric properties, and reduced extracted ion concentration, making it suitable for sealing electrical and electronic components that require reliability, as well as circuit board materials.

1 shows a GPC chart of the epoxy resin obtained in Example 1.

The present invention is described in detail below.

ここで、ｎは繰り返し数であり、０～２０の数を示し、Ｇはグリシジル基である。好ましくは、ｎの値が異なる成分の混合物である。単官能のｎ＝０の成分が多いと硬化物の耐熱性が低下してしまうため、ｎ＝０の成分は３０％以下であることが好ましい。ｎは、平均値（数平均）として、好ましくは０．５～５．０の範囲である。
Ｒ^１、Ｒ^２は独立して水素原子または炭素数１～１０の一価の炭化水素基を示す。Ｒ^１、Ｒ^２は、狙いとする特性で好ましい範囲が異なる。低誘電率、低誘電正接を下げるためにはかさ高い構造が好ましく、炭素数７～１０の一価の炭化水素基が好ましい。一方、かさ高い一価の置換基は立体障害となり、反応性を低下させてしまうことから、反応性の面では、水素原子または炭素数１～３の一価の炭化水素基が好ましい。
一般式（１）で表されるエポキシ樹脂は、エポキシ当量（ｇ／ｅｑ.）が、好ましくは２７０～４５０、より好ましくは２８０～４００である。 The epoxy resin of the present invention is represented by the general formula (1) and has an epoxy equivalent (g/eq.) of 250 to 500.

Here, n is the number of repetitions, which is a number between 0 and 20, and G is a glycidyl group. Preferably, it is a mixture of components with different values of n. If there is a large amount of monofunctional n=0 components, the heat resistance of the cured product decreases, so it is preferable that the content of n=0 components is 30% or less. n is preferably in the range of 0.5 to 5.0 as an average value (number average).
R ¹ and R ² are independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. The preferred ranges of R ¹ and R ² differ depending on the targeted properties. To reduce the dielectric constant and dielectric tangent, a bulky structure is preferred, and a monovalent hydrocarbon group having 7 to 10 carbon atoms is preferred. On the other hand, a bulky monovalent substituent becomes a steric hindrance and reduces reactivity, so from the standpoint of reactivity, a hydrogen atom or a monovalent hydrocarbon group having 1 to 3 carbon atoms is preferred.
The epoxy resin represented by the general formula (1) has an epoxy equivalent (g/eq.) of preferably 270 to 450, and more preferably 280 to 400.

From the viewpoint of solvent solubility and melt-kneadability, the epoxy resin of the present invention preferably has a softening point of 100°C or less and does not exhibit crystallinity. If the softening point is higher than 100°C, the melt-kneadability decreases, and if the resin has crystallinity, the solvent solubility also decreases. If the resin is liquid or semi-solid, the composition can be easily homogenized, and although handling is difficult when used alone, it can be adjusted by blending the composition. The softening point is preferably 80°C or less.

The epoxy resin of the present invention preferably has a melt viscosity of 0.15 Pa·s or less, more preferably 0.10 Pa·s or less. The total chlorine content is preferably 1000 ppm or less, more preferably 700 ppm or less.

ここで、ｎ、Ｒ^１、Ｒ^２は、一般式（１）において記載した意味と同じである。多価ヒドロキシ樹脂の水酸基（ＯＨ基）が、エポキシ樹脂のグリシジル含有基（ＯＧ基）に変更される以外、多価ヒドロキシ樹脂の構造は、エポキシ樹脂においても実質的に反映される。 The epoxy resin of the present invention can be produced by reacting a polyhydric hydroxy resin represented by the general formula (2) with epichlorohydrin.

Here, n, R ¹ and R ² have the same meanings as those described in the general formula (1). The structure of the polyhydric hydroxyl resin is substantially reflected in the epoxy resin, except that the hydroxyl group (OH group) of the polyhydric hydroxyl resin is changed to the glycidyl-containing group (OG group) of the epoxy resin.

The polyhydric hydroxyl resin represented by general formula (2) preferably has an OH group equivalent (g/eq.) of 200 to 400, more preferably 210 to 350, and even more preferably 220 to 330.

The method for producing the epoxy resin of the present invention by reacting the polyhydric hydroxy resin represented by the above general formula (2) with epichlorohydrin will be described. This reaction can be carried out in the same manner as the well-known epoxidation reaction. For example, the polyhydric hydroxy resin is dissolved in excess epichlorohydrin, and then reacted for 1 to 10 hours at 50 to 150°C, preferably 60 to 120°C, in the presence of an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide. The amount of epichlorohydrin used in this case is 0.8 to 2 moles, preferably 0.9 to 1.2 moles, per mole of hydroxyl group in the polyhydric hydroxy resin. After the reaction is completed, the excess epichlorohydrin is distilled off, and the residue is dissolved in a solvent such as toluene or methyl isobutyl ketone, filtered, washed with water to remove inorganic salts, and then the solvent is distilled off to obtain the desired epoxy resin represented by the above general formula (1). A catalyst such as a quaternary ammonium salt may be used when carrying out the epoxidation reaction.

ここで、Ｘは水酸基、ハロゲン原子又は炭素数１～６のアルコキシ基を示す。 This polyhydric hydroxy resin can be produced by reacting a hydroxybiphenyl with an aromatic condensing agent having a biphenyl structure represented by the following general formula (3).

Here, X represents a hydroxyl group, a halogen atom or an alkoxy group having 1 to 6 carbon atoms.

Examples of hydroxybiphenyls, which are raw materials for synthesizing polyhydric hydroxy resins, include 2-phenylphenol, 4-phenylphenol, 3-benzyl-1,1'-biphenyl-2-ol, 3-benzyl-1,1'-biphenyl-4-ol, 3-phenylphenol, and 2,6-diphenylphenol. In terms of reactivity and supplyability, 2-phenylphenol and 4-phenylphenol are preferred.

In the aromatic condensing agent represented by the general formula (3), X represents a hydroxyl group, a halogen atom, or an alkoxy group having 1 to 6 carbon atoms. Specific examples of aromatic condensing agents include 4,4'-bishydroxymethylbiphenyl, 4,4'-bischloromethylbiphenyl, 4,4'-bisbromomethylbiphenyl, 4,4'-bismethoxymethylbiphenyl, and 4,4'-bisethoxymethylbiphenyl. From the viewpoint of reactivity, 4,4'-bishydroxymethylbiphenyl or 4,4'-bischloromethylbiphenyl is preferred, and from the viewpoint of reducing ionic impurities, 4,4'-bishydroxymethylbiphenyl or 4,4'-bismethoxymethylbiphenyl is preferred.

The molar ratio when reacting biphenols with aromatic condensing agents is generally in the range of 0.1 to 0.5 moles of aromatic condensing agent per mole of biphenols, and more preferably in the range of 0.2 to 0.4 moles. If it is less than 0.1 moles, the ratio of n=0 in the resulting polyhydric hydroxyl resin will be high, and there is concern that it will exhibit crystallinity and thus reduce solubility. On the other hand, if it is more than 0.5 moles, the softening point and melt viscosity will increase due to the high molecular weight, which will hinder handling, workability, and moldability. In addition, if the aromatic condensing agent is more than 0.5 moles, by-products such as aromatic condensing agents with one end unreacted will be produced, and there is concern that this will reduce heat resistance and reactivity.

The reaction between biphenols and aromatic condensing agents can be carried out without a catalyst or in the presence of an acid catalyst such as an inorganic acid or an organic acid. When using 4,4'-bischloromethylbiphenyl, the reaction can be carried out without a catalyst, but it is generally better to carry out the reaction in the presence of an acid catalyst in order to suppress side reactions such as the reaction of a chloromethyl group with a hydroxyl group to form an ether bond. The acid catalyst can be appropriately selected from well-known inorganic and organic acids, and examples of the acid catalyst include mineral acids such as hydrochloric acid, sulfuric acid, and phosphoric acid, organic acids such as formic acid, oxalic acid, trifluoroacetic acid, p-toluenesulfonic acid, methanesulfonic acid, and trifluoromethasulfonic acid, Lewis acids such as zinc chloride, aluminum chloride, iron chloride, and boron trifluoride, and solid acids.

This reaction is usually carried out at 100 to 250°C for 1 to 20 hours. It is preferably carried out at 100 to 180°C, and more preferably at 140 to 180°C. If the reaction temperature is low, the reactivity is poor and it takes a long time, and if the reaction temperature is high, there is a risk of the resin decomposing.

As a solvent for the reaction, for example, alcohols such as methanol, ethanol, propanol, butanol, ethylene glycol, methyl cellosolve, ethyl cellosolve, diethylene glycol dimethyl ether, triglyme, etc., or aromatic compounds such as benzene, toluene, chlorobenzene, dichlorobenzene, etc. are preferably used, and among these, ethyl cellosolve, diethylene glycol dimethyl ether, triglyme, etc. are particularly preferred. After the reaction is completed, the solvent may be removed from the obtained polyhydric hydroxyl resin by methods such as vacuum distillation, washing with water, or reprecipitation in a poor solvent, but the solvent may be left as it is and used as a raw material for the epoxidation reaction.

The polyhydric hydroxyl resin represented by the general formula (2) thus obtained can be used not only as a raw material for epoxy resins but also as an epoxy resin curing agent. In this case, it is desirable that the polyhydric hydroxyl resin represented by the general formula (2) is contained in an amount of 50 wt % or more, more preferably 70 wt % or more, and even more preferably 80 wt % or more of the total curing agent.
Furthermore, by combining it with a hardener such as hexamine, it can also be used as a phenolic resin molding material.

In addition to the epoxy resin of general formula (1) used as an essential component, the epoxy resin composition of the present invention may contain other ordinary epoxy resins having two or more epoxy groups in the molecule. Examples include bisphenol A, bisphenol F, 3,3',5,5'-tetramethyl-4,4'-dihydroxydiphenylmethane, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxydiphenyl ketone, fluorene bisphenol, 4,4'-biphenol, 3,3',5,5'-tetramethyl-4,4'-dihydroxybiphenyl, 2,2'-biphenol, resorcinol, catechol, t-butyl catechol, etc. t-Butylhydroquinone, 1,2-dihydroxynaphthalene, 1,3-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 1,7-dihydroxynaphthalene, 1,8-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2,4-dihydroxynaphthalene, 2,5-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 2,8-dihydroxy Naphthalene, allyl or polyallyl products of the above dihydroxynaphthalene, dihydric phenols such as allyl bisphenol A, allyl bisphenol F, and allyl phenol novolac, or phenol novolac, bisphenol A novolac, o-cresol novolac, m-cresol novolac, p-cresol novolac, xylenol novolac, poly-p-hydroxystyrene, tris-(4-hydroxyphenyl)methane, 1,1,2,2-tetrakis Examples of such epoxy resins include glycidyl ethers derived from trivalent or higher phenols such as (4-hydroxyphenyl)ethane, fluoroglycinol, pyrogallol, t-butylpyrogallol, allylated pyrogallol, polyallylated pyrogallol, 1,2,4-benzenetriol, 2,3,4-trihydroxybenzophenone, phenol aralkyl resins, naphthol aralkyl resins, and dicyclopentadiene-based resins, or halogenated bisphenols such as tetrabromobisphenol A. These epoxy resins can be used alone or in combination of two or more.

The epoxy resin composition of the present invention preferably contains the epoxy resin of the above general formula (1) as the epoxy resin in an amount of 50 wt% or more of the epoxy resin component. More preferably, it is 70 wt% or more, and even more preferably 80 wt% or more of the total epoxy resin. If the proportion used is less than this, the moldability of the epoxy resin composition deteriorates, and the effect of improving the low dielectric properties and reliability of the cured product is small.

As the curing agent used in the epoxy resin composition of the present invention, any agent generally known as a curing agent for epoxy resins can be used, such as dicyandiamide, acid anhydrides, polyhydric phenols, aromatic and aliphatic amines, etc. Among these, it is preferable to use polyhydric phenols as a curing agent in fields that require high electrical insulation, such as semiconductor encapsulants. Specific examples of curing agents are shown below.

Examples of polyhydric phenols include dihydric phenols such as bisphenol A, bisphenol F, bisphenol S, fluorene bisphenol, 4,4'-biphenol, 2,2'-biphenol, hydroquinone, resorcin, and naphthalenediol, as well as trihydric or higher phenols such as tris-(4-hydroxyphenyl)methane, 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane, phenol novolac, o-cresol novolac, naphthol novolac, and polyvinylphenol. Further examples include polyhydric phenolic compounds synthesized from dihydric phenols such as phenols, naphthols, bisphenol A, bisphenol F, bisphenol S, fluorene bisphenol, 4,4'-biphenol, 2,2'-biphenol, hydroquinone, resorcin, and naphthalenediol, and condensing agents such as formaldehyde, acetaldehyde, benzaldehyde, p-hydroxybenzaldehyde, and p-xylylene glycol.

Examples of acid anhydride hardeners include phthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylhimic anhydride, dodecylsuccinic anhydride, nadic anhydride, and trimellitic anhydride.

Amine-based curing agents include aromatic amines such as 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenylsulfone, m-phenylenediamine, and p-xylylenediamine, and aliphatic amines such as ethylenediamine, hexamethylenediamine, diethylenetriamine, and triethylenetetramine.

The above epoxy resin composition can be used with one or more of these curing agents mixed together.

The mixing ratio of epoxy resin to hardener is preferably in the range of 0.8 to 1.5 in terms of the equivalent ratio of epoxy groups to functional groups in the hardener. Outside this range, unreacted epoxy groups or functional groups in the hardener remain even after hardening, which is undesirable as it reduces the reliability of the sealing function.

In the epoxy resin composition of the present invention, oligomers or polymeric compounds such as polyester, polyamide, polyimide, polyether, polyurethane, petroleum resin, indene resin, indene-cumarone resin, and phenoxy resin may be appropriately blended as other modifiers. The amount added is usually in the range of 1 to 30 parts by weight per 100 parts by weight of the total resin components.

Additives such as inorganic fillers, pigments, flame retardants, thixotropy agents, coupling agents, and flow improvers can be blended into the epoxy resin composition of the present invention. Examples of inorganic fillers include silica powders such as spherical or crushed fused silica and crystalline silica, alumina powder, glass powder, mica, talc, calcium carbonate, alumina, hydrated alumina, boron nitride, and aluminum nitride. When used as a semiconductor encapsulant, the preferred blending amount is 70% by weight or more, and more preferably 80% by weight or more.

Pigments include organic or inorganic extender pigments, scaly pigments, etc. Thixotropic agents include silicone-based, castor oil-based, aliphatic amide wax, oxidized polyethylene wax, organic bentonite-based, etc.

Furthermore, a curing accelerator can be used in the epoxy resin composition of the present invention as needed. Examples of the organic phosphines include amines, imidazoles, organic phosphines, Lewis acids, and the like. Specific examples of the organic phosphines include tertiary amines such as 1,8-diazabicyclo(5,4,0)undecene-7, triethylenediamine, benzyldimethylamine, triethanolamine, dimethylaminoethanol, and tris(dimethylaminomethyl)phenol; imidazoles such as 2-methylimidazole, 2-phenylimidazole, 2-ethyl-4-methylimidazole, 2-phenyl-4-methylimidazole, and 2-heptadecylimidazole; organic phosphines such as tributylphosphine, methyldiphenylphosphine, triphenylphosphine, diphenylphosphine, and phenylphosphine; tetra-substituted phosphonium tetra-substituted borates such as tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium ethyltriphenylborate, and tetrabutylphosphonium tetrabutylborate; and tetraphenylboron salts such as 2-ethyl-4-methylimidazole tetraphenylborate and N-methylmorpholine tetraphenylborate. The amount added is usually in the range of 0.01 to 5 parts by weight per 100 parts by weight of the total resin components.

If necessary, the epoxy resin composition of the present invention may further contain release agents such as carnauba wax and OP wax, coupling agents such as γ-glycidoxypropyltrimethoxysilane, colorants such as carbon black, flame retardants such as antimony trioxide, stress reducers such as silicone oil, and lubricants such as calcium stearate.

The epoxy resin composition of the present invention can be made into a varnish state by dissolving an organic solvent in it, and then impregnating it into a fibrous material such as glass cloth, aramid nonwoven fabric, or polyester nonwoven fabric such as liquid crystal polymer, followed by removing the solvent to form a prepreg. In some cases, it can also be made into a laminate by applying it onto a sheet-like material such as copper foil, stainless steel foil, polyimide film, or polyester film.

The epoxy resin composition of the present invention can be heated and cured to produce the cured resin of the present invention. This cured product can be obtained by molding the epoxy resin composition using a method such as casting, compression molding, or transfer molding. The temperature used for this is usually in the range of 120 to 220°C.

The present invention will be specifically explained below with reference to synthesis examples, working examples, and comparative examples. However, the present invention is not limited to these. Unless otherwise specified, "parts" refers to parts by weight, and "%" refers to % by weight. In addition, the measurements were performed by the following methods.

1) Measurement of epoxy equivalent Using a potentiometric titrator, methyl ethyl ketone was used as a solvent, a tetraethylammonium bromide acetate solution was added, and the measurement was performed using a 0.1 mol/L perchloric acid-acetic acid solution with the potentiometric titrator.

2) OH equivalent: Using a potentiometric titrator, acetylation was carried out with 1.5 mol/L acetyl chloride using 1,4-dioxane as a solvent, and excess acetyl chloride was decomposed with water and titrated with 0.5 mol/L potassium hydroxide.

3) Melt Viscosity The melt viscosity was measured at 150° C. using a CAP2000H rotational viscometer manufactured by BROOKFIELD.

4) Softening point: Measured by the ring and ball method in accordance with JIS-K-2207.

5) GPC Measurement A main body (HLC-8220GPC, manufactured by Tosoh Corporation) equipped with columns (TSKgel G4000HXL, TSKgel G3000HXL, TSKgel G2000HXL, manufactured by Tosoh Corporation) in series was used, and the column temperature was set to 40°C. Tetrahydrofuran (THF) was used as the eluent, the flow rate was set to 1 mL/min, and a differential refractive index detector was used as the detector. The measurement sample was 50 μL of a sample obtained by dissolving 0.1 g of sample in 10 mL of THF and filtering through a microfilter. Data processing was performed using GPC-8020 Model II version 6.00 manufactured by Tosoh Corporation.

6) 5% weight loss temperature (Td5), carbon residue ratio Using a thermogravimetric/differential thermal analyzer (EXSTAR6000TG/DTA6200, manufactured by SII Nano Technology), the 5% weight loss temperature (Td5) was measured under conditions of a nitrogen atmosphere and a heating rate of 10°C/min. The weight loss at 700°C was also measured and calculated as the carbon residue ratio.

7) Dielectric constant and dielectric loss tangent Dielectric constant and dielectric loss tangent: Evaluated by determining the dielectric constant and dielectric loss tangent at a frequency of 1 GHz by a capacitance method using a material analyzer (manufactured by AGILENT Technologies) in accordance with IPC-TM-650 2.5.5.9.

8) Water Absorption Rate The standard conditions were 25° C. and 50% relative humidity, and the weight change rate after absorbing moisture for 100 hours under conditions of 85° C. and 85% relative humidity was measured.

9) Total chlorine: 1.0 g of a sample was dissolved in 25 ml of butyl carbitol, 25 ml of 1N KOH propylene glycol solution was added, and the mixture was heated under reflux for 10 minutes. The mixture was then cooled to room temperature, and 100 ml of 80% acetone water was added. The total chlorine was measured by potentiometric titration with a 0.002N AgNO3 aqueous solution.

10) Extracted chloride ion 10 g of cured epoxy resin material having a uniform particle size and 50 g of ion-exchanged pure water were weighed into a pressure vessel, and then subjected to heating and extraction. The chloride ion concentration in the extracted water was determined using ion chromatography, and the extracted chloride ion concentration of the cured epoxy resin material was calculated.

Example 1
In a 1000 ml four-neck flask, 100.0 g of 2-phenylphenol and 44.2 g of 4,4'-bischloromethylbiphenyl were charged, and the mixture was heated to 170°C while stirring under a nitrogen stream and reacted for 2 hours to produce a polyhydric hydroxy resin with an OH equivalent of 228 g/eq. After the reaction was completed, 48.8 g of diethylene glycol dimethyl ether was added, 325.2 g of epichlorohydrin was added, and 49.0 g of 48% aqueous sodium hydroxide solution was added dropwise over 3 hours at 62°C under reduced pressure (about 130 Torr). During this time, the water produced was removed from the system by azeotropy with epichlorohydrin, and the distilled epichlorohydrin was returned to the system. After the dropwise addition was completed, the reaction was continued for another hour. Thereafter, epichlorohydrin was distilled off, toluene was added and dissolved, the salt was removed by washing with water, and the mixture was filtered and washed with water. The toluene was then distilled off under reduced pressure to obtain 149 g of a semi-solid epoxy resin (epoxy resin A). This epoxy resin A had an epoxy equivalent of 292 g/eq, a softening point of 50° C. or less, a melt viscosity of 0.05 Pa s, and a total chlorine content of 130 ppm. The GPC chart of the obtained resin is shown in FIG.

Example 2
In a 1000 ml four-neck flask, 100.0 g of 2-phenylphenol and 59.0 g of 4,4'-bischloromethylbiphenyl were charged, and the mixture was heated to 170°C while stirring under a nitrogen stream and reacted for 2 hours to produce a polyhydric hydroxy resin with an OH equivalent of 247 g/eq. After the reaction was completed, 48.8 g of diethylene glycol dimethyl ether was added, 325.2 g of epichlorohydrin was added, and 48.9 g of 48% aqueous sodium hydroxide solution was added dropwise over 3 hours at 62°C under reduced pressure (about 130 Torr). During this time, the water produced was removed from the system by azeotropy with epichlorohydrin, and the distilled epichlorohydrin was returned to the system. After the dropwise addition was completed, the reaction was continued for another hour. Thereafter, epichlorohydrin was distilled off, toluene was added and dissolved, the salt was removed by washing with water, and the mixture was filtered and washed with water, and then the toluene was distilled off under reduced pressure to obtain 156 g of a semi-solid epoxy resin (epoxy resin B). This epoxy resin B had an epoxy equivalent of 324 g/eq, a softening point of 50° C. or less, a melt viscosity of 0.09 Pa s, and a total chlorine content of 450 ppm.

Example 3
The reaction was carried out in the same manner as in Example 1, except that 100.0 g of 4-phenylphenol was used instead of 2-phenylphenol, and 16.0 g of diethylene glycol dimethyl ether was added at the time of charging, to produce a polyhydric hydroxyl resin epoxy resin with an OH equivalent of 231 g/eq, which was then epoxidized to obtain 148 g of epoxy resin (epoxy resin C). The epoxy equivalent of this epoxy resin C was 294 g/eq, the softening point was 52°C, the melt viscosity was 0.03 Pa s, and the total chlorine was 680 ppm.

Example 4
In a 1000 ml four-neck flask, 100.0 g of 3-benzyl-1,1'-biphenyl-2-ol and 29.0 g of 4,4'-bischloromethylbiphenyl were charged, and the mixture was heated to 170°C while stirring under a nitrogen stream and reacted for 2 hours to produce a polyhydric hydroxy resin with an OH equivalent of 318 g/eq. After the reaction was completed, 31.9 g of diethylene glycol dimethyl ether was added, 212.5 g of epichlorohydrin was added, and 31.9 g of 48% aqueous sodium hydroxide solution was added dropwise at 62°C under reduced pressure (about 130 Torr) over 3 hours. During this time, the water produced was removed from the system by azeotropy with epichlorohydrin, and the distilled epichlorohydrin was returned to the system. After the dropwise addition was completed, the reaction was continued for another 1 hour. Thereafter, epichlorohydrin was distilled off, toluene was added and dissolved, the salt was removed by washing with water, and the mixture was filtered and washed with water, and then the toluene was distilled off under reduced pressure to obtain 126 g of a semi-solid epoxy resin (epoxy resin D). This epoxy resin D had an epoxy equivalent of 389 g/eq, a softening point of 50° C. or less, a melt viscosity of 0.04 Pa s, and a total chlorine content of 650 ppm.

Comparative Example 1
In a 1000 ml four-neck flask, 80.0 g of phenol and 85.4 g of 4,4'-bischloromethylbiphenyl were charged, and the mixture was heated to 170°C while stirring under a nitrogen stream and reacted for 2 hours to produce a polyhydric hydroxy resin with an OH equivalent of 167 g/eq. After the reaction was completed, 58.8 g of diethylene glycol dimethyl ether was added, 391.9 g of epichlorohydrin was added, and 70.9 g of 48% aqueous sodium hydroxide solution was added dropwise over 3 hours at 62°C under reduced pressure (about 130 Torr). During this time, the water produced was removed from the system by azeotropy with epichlorohydrin, and the distilled epichlorohydrin was returned to the system. After the dropwise addition was completed, the reaction was continued for another hour. Thereafter, epichlorohydrin was distilled off, toluene was added and dissolved, the salt was removed by washing with water, and the mixture was filtered and washed with water, and then the toluene was distilled off under reduced pressure to obtain 156 g of a semi-solid epoxy resin (epoxy resin E). This epoxy resin E had an epoxy equivalent of 236 g/eq, a softening point of 56° C., a melt viscosity of 0.09 Pa s, and a total chlorine content of 1210 ppm.

Comparative Example 2
In a 1000 ml four-neck flask, 77.5 g of 4,4'-dihydroxybiphenyl, 119.3 g of diethylene glycol dimethyl ether, and 41.8 g of 4,4'-bischloromethylbiphenyl were charged, and the mixture was heated to 160°C under nitrogen flow while stirring, and reacted for 20 hours to produce a polyhydric hydroxy resin with an OH equivalent of 135 g/eq. After the reaction was completed, 45.6 g of diethylene glycol dimethyl ether was recovered, 455.1 g of epichlorohydrin was added, and 70.5 g of a 48% aqueous sodium hydroxide solution was added dropwise over 4 hours at 62°C under reduced pressure (about 130 Torr). During this time, the water produced was removed from the system by azeotropy with epichlorohydrin, and the distilled epichlorohydrin was returned to the system. After the dropwise addition was completed, the reaction was continued for another hour. Thereafter, epichlorohydrin was distilled off, methyl isobutyl ketone was added, and the salt was removed by washing with water, followed by filtration and washing with water, and then methyl isobutyl ketone was distilled off under reduced pressure to obtain 129 g of epoxy resin (epoxy resin F). This epoxy resin F had an epoxy equivalent of 200 g/eq, a softening point of 125° C., a melt viscosity of 0.21 Pa s, and a total chlorine content of 2300 ppm.

Solvent solubility Solvent solubility was judged by adding epoxy resins A to D obtained in Examples 1 to 4 and epoxy resins E and F obtained in Comparative Examples 1 and 2 to 5 g of solvent (methyl ethyl ketone, toluene, cyclohexanone) so that the solid content concentration (g epoxy resin/100 g solvent) was 50% by weight, thoroughly stirring at room temperature, and then visually checking for insoluble matter. The presence of insoluble matter was marked with ×, and the absence of insoluble matter was marked with ◯. The results are shown in Table 1.

Examples 5 to 10 and Comparative Examples 1 to 3
As the epoxy resin components, epoxy resins A to D obtained in Examples 1 to 4, epoxy resins E and F obtained in Comparative Examples 1 and 2, and o-cresol novolac type epoxy resin (YDCN-700-3 manufactured by Nippon Steel Chemical & Material, epoxy equivalent 200 g/eq, total chlorine 1600 ppm) were used as epoxy resin G, phenol novolac resin (OH equivalent 105 g/eq, softening point 67°C) was used as curing agent A, the polyhydric hydroxyl resin obtained in Example 1 was used as curing agent B (OH equivalent 228 g/eq, softening point 60°C), and triphenylphosphine was used as a curing accelerator, and epoxy resin compositions were obtained with the formulation shown in Table 2. The values in the table indicate the parts by weight in the formulation. In order to obtain a uniform molded product, the melt-kneading temperature was 100°C in Examples 5 to 10 and Comparative Example 1, and 150°C in Comparative Examples 2 and 3.
This epoxy resin composition was molded at 175° C. and post-cured at 175° C. for 5 hours to obtain test pieces of the cured product, which were then subjected to measurements of various physical properties.

As is clear from these results, the epoxy resins obtained in the examples have excellent solvent solubility, the chlorine content of the resin itself is specifically low, and the cured products thereof have thermal stability, low water absorption, low dielectric constant, low dielectric dissipation factor, and low amount of chlorine ions extracted from water, and are therefore suitable for use as electronic materials such as substrates and sealing materials.

Claims (5)

An epoxy resin represented by the following general formula (1), characterized in that the epoxy resin has an epoxy equivalent in the range of 250 to 500 g/eq.

(Here, n is a number from 0 to 20, G is a glycidyl group, and R ¹ and R ² are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. A polyhydric hydroxy resin represented by the following general formula (2), characterized in that the OH equivalent is in the range of 200 to 450 g/eq.

(Here, n is a number from 0 to 20, and R ¹ and R ² are independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. An epoxy resin composition comprising an epoxy resin and a curing agent, the epoxy resin being characterized in that it contains the epoxy resin according to claim 1 as an essential component as part or all of the epoxy resin. A resin composition comprising the polyhydric hydroxyl resin according to claim 2 as an essential component. A cured resin product obtained by curing the resin composition according to claim 3 or 4.

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